Acrylonitrile monomer is a basic building block for a number of very important polymers. By polymerizing acrylonitrile polyacrylonitrile may be obtained. It is a white fiber that has a very good resistance to acids, common solvents, oils, greases, salts, and sunlight. Nitrile rubbers which have excellent abrasion, oil and chemical resistance are prepared by the copolymerization of butadiene and acrylonitrile. Acrylonitrile monomer can be utilized in a great many other copolymers and terpolymers.
After the synthesis of a polymer that contains linkages that are derived from acrylonitrile is completed some unpolymerized acrylonitrile monomer will still be present. Polymers that contain acrylonitrile linkages, acrylonitrile polymers, are normally synthesized by emulsion polymerization in an aqueous system. The unpolymerized residual acrylonitrile normally remains in both the acrylonitrile polymer itself and in the water. The normal procedure of stripping by vacuuming or steam does not usually remove all of this undesirable residual acrylonitrile. Since acrylonitrile is believed to be toxic through the cyanide effect it would be highly desirable to remove substantially all free residual acrylonitrile.
Most polymers are susceptible to oxidative and photo-initiated degradation which decrease their service life. This deterioration occurs during fabrication, storage and use. This degradation is commonly caused by heat, ionizing radiation, mechanical stress, or chemical reactions which cause chemical bonds in the polymer to break and the formation of free radicals. A complex sequence of chemical reactions is generally involved in the degradation of a polymer. Either by breaking the polymers chain and/or crosslinking, the polymer's molecular weight is usually changed very substantially. Such a deterioration can render a polymer totally unsuitable for the purpose for which it was intended. For this reason most polymers normally require the addition of an antioxidant in order to minimize the possibility of degradation.